This invention relates to the field of locks for the valves beneath the storage tanks of tank trucks to prevent unauthorized or accidental opening of the valve and emptying of the contents of the storage tank.
Prior art valve locks have included the angled or stepped member disclosed in U.S. Pat. No. 4,397,332 secured at one end to the valve outlet and the other end being received between spokes of the valve operator or valve handle.
U.S. Pat. No. 1,550,487 discloses a strap member pivotally mounted to a portion of the valve body at one end for movement between a valve locking position and a valve release position, the strap member having a V-notch in an intermediate portion which is in registration with the angular shaft of the valve operator when pivoted to the valve locking position. The other end of the strap member includes an aperture to receive the loop or hook member 30 projecting from a portion of the valve body, after which a padlock can be locked in place through the member 30 to hold the strap member in valve locking position against the angular shaft of the valve operator to prevent it from being turned.
U.S. Pat. No. 1,496,096 discloses a lever assembly to raise and lower the fill pipe 10 of a fluid filling standpipe for locomotives in which the valve operator can be locked when the fill pipe 10 is raised outwardly from the fill port of a locomotive's tank.
U.S. Pat. No. 1,339,083 discloses an outlet valve mechanism for tank cars in which the shackle of a padlock can be placed between the spokes of the hand wheel of the valve operator and through the aperture of a strap member positioned adjacent thereto, whereby the hand wheel cannot be rotated until the padlock is removed.
U.S. Pat. No. 1,293,095 discloses an automobile lock in which a valve is mounted in the fuel line between the gasoline tank and the carbureter with the valve stem projecting upwardly through the floor board of the car for rotating between a valve closed and valve open position. The free end of the valve stem includes a ring or eyelet to receive the shackle of a padlock when in the valve closed position, the shackle also passing through a corresponding eyelet of an anchor post to thereby lock the valve stem in the valve closed position.
None of the prior art devices include the feature of an intermediate portion of the lock device bearing against a portion of the valve body to further restrain movement of the valve operator toward the valve opening position. Such prior art lock devices can therefore be more easily forced and broken. The present invention solves that problem.